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Turning Coffee Grounds Into Biofuel Is More Efficient Than Ever

May 25, 2017

Written byCuriosity Staff

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For a lot of us at the Curiosity offices, coffee is the only thing that gets us going in the morning...and afternoon, and evening, and in the middle of the night when we're trying to wrap our minds around quantum physics. But soon, it might be the get-up-and-go drink of choice for vehicles as well, since researchers at Lancaster University have devised an efficient way to make biofuel from used coffee grounds. Maybe we'll have to start buying our cars donuts, too.

A Reliable Method, Perfected

Making biofuel out of coffee grounds isn't new, but it's always been a bit costly—both in money and, strangely, in costs to the environment. Previously, rendering burnable oil from coffee grounds was a multi-stage process of mixing the grounds with hexane, cooking the hexane off to leave only the oil, which is then mixed with methanol and a catalyst to produce biodiesel. That hexane that gets disposed of has nowhere to go, though, and that means that the process of making this supposedly green fuel is actually polluting the environment. Dr. Vesna Najdanovic-Visak and her team at Lancaster University have been able to circumvent that first step and cut down the chemical waste of the process. Their work has proved extremely fruitful, and they've been able to make their biofuel both cheaper and faster than the old way of doing things.

How viable is this method for actually fueling the cars of the world? To answer that question, we've got to figure out how many coffee grounds we produce, and how much fuel we can squeeze out of the coffee grounds we process. According to a report from the American Chemical Society, spent coffee grounds are comprised of approximately 11–20 percent oil, which is comparable to traditional biodiesel crops such as palm and soybeans. Both the old process and the new one are capable of pulling out 100 percent of that oil, so the real challenge is gathering all of those grounds instead of letting them languish in a landfill. If we were capable of snapping our fingers and transporting all of the used grounds to a processing plant, then scientists estimate we'd be able to produce 340 gallons of biodiesel per year. Not enough to end the fuel crisis, but nothing to sneeze at either.

Making It Happen

Since there have already been processes in place for converting coffee grounds into biodiesel, it's probably not surprising that there are a multitude of companies making use of the caffeinated resource. This improved method will only streamline their process. In London, bio-bean has made an art out of acquiring the leftovers from major coffee producers. In fact, they processed the grounds of one out of every 10 coffees Great Britain drank in 2015. The fuel they make doesn't just go into eco-friendly cars, either. It's also used to make carbon-neutral briquettes for grilling and so-called "coffee logs" to burn in a fireplace. Seems like coffee is good for warming more than just our cold, sleep-deprived hearts.